Expandable pipe including a liner for restoring a conduit

ABSTRACT

An expandable pipe for restoring a damaged pipe is provided. The expandable pipe includes a liner formed of thermoplastic polyurethane, and grout material applied to the exterior surface of the liner. The exterior surface includes a plurality of flared tips and grooves, and each groove is located between adjacent flared tips. The grout material is disposed on the flared tips and in the grooves of the liner. The method used to restore the damaged pipe includes clamping the liner with the grout material on a puller-sealer fixture having a U-shaped cross-section to prevent debris from entering the interior of the liner, and pulling the puller-sealer fixture and liner through the damaged pipe. The grout material expands in volume upon exposure to moisture, ultra violet radiation, heat, and/or ultrasonics, and fills cracks or other imperfections and voids along the interior surface of the conduit, caused by corrosion, erosion, or other circumstances.

CROSS-REFERENCE TO RELATED APPLICATIONS

This U.S. utility patent application claims priority to U.S. provisionalpatent application No. 62/289,760, filed Feb. 1, 2016, and U.S.provisional patent application No. 62/432,265, filed Dec. 9, 2016, thecontents of which are incorporated herein by reference in theirentirety.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The invention relates to products and methods for restoration of damagedconduits.

2. Related Art

Grout materials are often used to repair an interior surface ofcorroded, cracked, or otherwise damaged conduit. One method of repairinga metal conduit includes coupling short links of stainless steel sleevesto one another to form a liner, and pulling the stainless steel linerthrough the metal conduit with a cable to present a small annular spacebetween the stainless steel liner and the metal conduit. A groutmaterial is then pumped into the annular space to fill the annular spaceand cracks in the metal conduit. However, this method includessignificant material costs and labor costs. Further, in the above methodand other methods currently used, controlling the placement of the groutmaterial is difficult. Oftentimes, the grout material is disposedunevenly along the damaged conduit and does not fill all of the cracksof the conduit.

Another more recently developed method for repairing damaged conduitswith a grout material includes the use of an expandable pipe. Theexpandable pipe includes a liner and the grout material disposed ingrooves along the exterior surface of the liner. The liner with thegrout material is disposed in an opening of the damaged conduit, andthen exposed to moisture such that the grout material expands andengages the interior surface of the damaged conduit.

The grooves of the liner allow for the expandable pipe to fold forconvenient transportation of the expandable pipe. The grooves alsoprovide flexibility for maneuvering the expandable pipe around bends ofthe damaged conduit. The grooves of the liner also allow for controlledplacement and amount of the grout material along the exterior surface ofthe liner. The grooves maintain the placement of the grout material asthe liner is disposed in the damaged conduit. The grout material expandsto engage the interior surface of the damaged conduit and fills cracks,holes, indentations, or other imperfections and voids along the interiorsurface of the conduit, caused by corrosion, erosion, or othercircumstances. In other words, the expandable pipe relines the interiorsurface of the damaged conduit. The expandable pipe also provides a sealto the conduit and prevents water and debris from entering the conduit.The grout material of the expandable pipe can also expand through holesin the conduit and fill voids in earth surrounding the conduit. Theexpandable pipe is a cost-effective and convenient way to repair andrestore conduits of various types, such as sewer pipes, potable waterpipes, electrical pipes, and air ducts. An example of the expandablepipe is disposed in U.S. Pat. No. 7,942,167.

SUMMARY

One aspect of the invention provides an expandable pipe for restoring adamaged pipe. The expandable pipe includes a liner formed of athermoplastic polyurethane and presenting an exterior surface. Theexterior surface of the liner includes a plurality of flared tips andgrooves, and each groove is located between adjacent flared tips. Agrout material is disposed on the flared tips and in the grooves of theliner. The grout material is expandable in a dimension upon exposure tomoisture, ultra violet radiation, heat, and/or ultrasonics.

According to another embodiment, the expandable pipe includes a linerformed of a polymer-based and/or elastomer-based material, and the linerincludes a plurality of fibers. The liner includes an exterior surface,and the exterior surface of the liner includes a plurality of grooves. Agrout material is disposed in the grooves of the liner, and the groutmaterial is expandable in a dimension upon exposure to moisture, ultraviolet radiation, heat, and/or ultrasonics.

Another aspect of the invention provides a method of manufacturing anexpandable pipe for restoring a damaged pipe. The method includesextruding a liner from a thermoplastic polyurethane, wherein theextruded liner includes an exterior surface with a plurality of flaredtips and grooves, each groove being located between adjacent flaredtips. The method further includes disposing a grout material on theflared tips and in the grooves of the liner, wherein the grout materialis expandable in a dimension upon exposure to moisture, ultra violetradiation, heat, and/or ultrasonics.

According to another embodiment, the method of manufacturing theexpandable pipe for restoring a damaged pipe comprises extruding a linerformed of a polymer-based and/or elastomer-based material and includinga plurality of fibers, wherein the extruded liner include an exteriorsurface with a plurality of grooves. The method further includesdisposing a grout material in the grooves of the liner, wherein thegrout material is expandable in a dimension upon exposure to moisture,ultra violet radiation, heat, and/or ultrasonics.

Yet another aspect of the invention provides a method of restoring adamaged pipe. The method includes providing a liner formed of apolymer-based and/or elastomer-based material, the liner including anexterior surface, and applying a grout material to the exterior surfaceof the liner. The method further includes disposing the liner on apuller-sealer fixture having a U-shaped cross-section, and pulling thepuller-sealer fixture and liner with the grout material through thedamaged pipe. The method further includes exposing the grout material onthe exterior surface of the liner to moisture, ultra violet radiation,heat, and/or ultrasonics, the exposing step causing the grout materialto expand and contact an inner diameter surface of the damaged pipe.

BRIEF DESCRIPTION OF THE DRAWINGS

Other advantages of the present invention will be readily appreciated,as the same becomes better understood by reference to the followingdetailed description when considered in connection with the accompanyingdrawings wherein:

FIG. 1 is a cross-sectional view of a portion of a liner according to anexample embodiment of the invention;

FIG. 2 is a cross-sectional view of the entire liner disposed inside ofa host pipe according to the example embodiment of the invention;

FIG. 3 is a cross-sectional view of a puller/sealer fixture disposedinside of the host pipe which configures the liner for passage throughthe host pipe with minimal interference with the inner diameter of thehost pipe and which seals an inner diameter of the liner from water,debris, and grout material;

FIG. 4 illustrates the puller/sealer fixture attached to a sprayingfixture and rolling dolly used to install the liner in the host pipe;

FIG. 5 illustrates an example of a dip tank assembly for coating theliner with a 1-part moisture-curing urethane grout according to anexample embodiment; and

FIG. 6 includes example specifications of a coating tank and a mixingtank of the dip tank assembly according to the example embodiment.

DETAILED DESCRIPTION OF EXAMPLE EMBODIMENTS

An expandable pipe 20 for restoring a damaged conduit 22, also referredto as a host pipe, is shown in FIGS. 1-13 of the related U.S.provisional patent application No. 62/289,760. The damaged conduit orhost pipe 22 is a pipe in the ground that requires rehabilitation. Forexample, the expandable pipe 20 can be used to repair or restoreconduits or host pipe 22 of various types, such as water conduits, gasconduits, oil conduits, sewer pipes, potable water pipes, electricalpipes, and air ducts.

The expandable pipe 20 includes an improved liner 24 formed of apolymer-based and/or elastomer-based material, and a grout material 30applied to an exterior surface 26 of the liner 24. The exterior surface26 of the liner 24 can include grooves 28 or a profiled surface tomaintain the grout material 30 in place as the liner 24 is disposed inthe host pipe 22. The grout material 30 expands in a dimension D₁, suchas volume, upon exposure to or contact with moisture, ultra violet (UV)radiation heat, and/or ultrasonics. Moisture, ultra violet radiation,heat, and/or ultrasonics are also able to cure the grout material 30.Thus, after such exposure, the grout material 30 contacts an innerdiameter surface of the damaged host pipe 22 and fills voids in thedamaged host pipe 22. The volume of the grout material 30 afterexpansion is 1% to 1000% greater than the volume of the grout material30 before expansion. The grout material 30 then hardens to restore theintegrity of the host pipe 22. In addition to the embodiments describedin U.S. provisional patent application No. 62/289,760, several otherembodiments are possible, which are described herein with reference toFIGS. 1-4 of the present application.

As stated above, the liner 24 is formed of a polymer-based and/orelastomer-based material. The liner 24 can be formed of a singlepolymer-based or elastomer-based material, for example a thermoplasticmaterial. Alternatively, the liner 24 can include more than one polymerand/or elastomer. According to example embodiments, the liner 24 isextruded from clear thermoplastic polyurethane (TPU). The clear liner 24is preferred for viewing purposes, for example to view the inside of thedamaged host pipe 22 being repaired using a video camera. However, theliner 24 could be another color and does not have to be clear tofunction as intended. The liner 24 could also have another composition.For example, the liner 24 could be formed of any material that can befolded then expanded, not limited to TPU. For example, the liner 24could be formed of polyethylene or any medium density plastic. The liner24 can optionally include fibers in the polymer-based and/orelastomer-based material, at least in a thin base portion of the liner24, to increase strength and prevent ballooning of the liner 24. Forexample, the liner 24 could include a composite of multiple polymersand/or elastomers, and reinforcing fibers. The visual clarity of the TPUallows for convenient video identification of lateral access points toallow for trimming of the liner 24. After installation of the liner 24in the host pipe 22, an interior diameter surface 32 of the liner 24located opposite the exterior surface 26 is smooth.

According to a preferred embodiment, the grooves 28 of the liner 24 areachieved by a profile on an exterior surface 26, also referred to as anouter diameter surface, of the liner 24, as shown in FIGS. 1 and 2. Inthe embodiment of FIGS. 1 and 2, the profile of the exterior surface 26of the liner 24 includes flared tips 34 which act as a mechanical lockfor the grout material 30 applied to the exterior surface 26 of theliner 24. FIG. 1 only shows the flared tips 34 along a portion of theexterior surface 26 of the liner 24, but the flared tips 34 arepreferably located along the entire exterior surface 26 of the liner 24,and continuously around the outer circumference of the liner 24. In theexample of FIGS. 1 and 2, each groove 28 is formed between two adjacentflared tips 34, and the grout material 30 is contained in those grooves28. The flared tips 34 include a stem 36 extending perpendicular to thebase of the liner 24, and an enlarged top 38 which flares outwardlyrelative to the stem 36. The diameter or width of the enlarged top 38 isgreater than the diameter or width of the stem 36. The flared tips 34shown in FIGS. 1 and 2 are only an example, as the shape and dimensionsof the flared tips 34 can vary. Alternatively, other profiled shapes anddimensions can be used to achieve the grooves 28 in the liner 24.However, the flared tips 34 or other mechanical locking features are notrequired if a sufficient bond between the liner 24 and the groutmaterial 30 is achieved.

The liner 24 can be formed by extrusion, preferably in a flat extrusiondie to produce a flat product, such as a sheet of the TPU or anotherthermoplastic material. The flat extruded product is then welded into acircular pipe shape to produce the liner 24 and so as to reside insidethe host pipe 22, as shown in FIG. 2. In other words, the flat productis welded it at a circumference that matches the required diameter forthe liner 24. The diameter of the liner 24 should be less than the innerdiameter of the host pipe 22 when the liner 24 is inflated. For example,the liner 24 of the example embodiment has a 7.5 inch inner diameterwhen inflated, and the host pipe 22 has an 8 inch inner diameter. Theliner 24 could be extruded to size, as a circular tube, however certainraw materials are difficult to extrude into circular geometries due to alack of melt strength. The other advantage of extruding flat and weldingis the ability to obtain any diameter with limited tooling.

According to the example embodiments, during installation of the liner24 in the host pipe 22, the grout material 30, preferably urethanegrout, such as an unactivated liquid polyurethane, is applied to theexterior surface 26 of the liner 24. The grout material 30 canoptionally include fibers to increase strength. At this point, the liner24 is folded flat for installation. Before the liner 24 enters the hostpipe 22, it is coated on the exterior surface 26 with 1-partmoisture-curing urethane grout. This grout material 30 cures and expandsduring installation, adhering to both the TPU liner 24 and the host pipe22.

As will be discussed further below, in the example embodiments, a 2-parturethane grout is sprayed onto the inner diameter surface of the hostpipe 22 during installation. In other words, urethane grout is sprayedonto the inner diameter surface of the host pipe 22 during installation,and as the TPU liner 24 is being pulled through the host pipe 22 by acable 40 and a rolling dolly 42, a set of mixing/spraying heads 44mounted to the rolling dolly 42 sprays the coating of 2-part urethanegrout (optionally including entrained fibers) onto the inner diametersurface of the host pipe 22 (just ahead of the liner 24 as it is pulledthrough the host pipe 22). The 2-part urethane grout includes 1-part ofthe urethane and 1-part of a curing agent. The 1-part expanding urethanegrout applied to the exterior surface 26 of the liner 24 before itenters the host pipe 22 combined with the 2-part expanding urethanegrout sprayed onto the inner diameter surface of the host pipe 22 as theliner 24 is pulled through the host pipe 22, serve to provide a highstrength, and highly adhesive interface between the liner 24 and thehost pipe 22, while also migrating and expanding to fill any cracks,voids or imperfections in the host pipe 22 or adjoining service lines.

The method of installing the liner 24 in the host pipe 22 according toexample embodiments will now be described in more detail with referenceto FIGS. 3 and 4. When the TPU liner 24 is ready for installation, it iscoiled, laying flat like a fire hose, onto reels. At the jobsite wherethe host pipe 22 is located, the liner 24 is routed through a dip (orsoaking) tank assembly 56 containing the 1-part moisture-curing urethanegrout. FIG. 5 illustrates the liner 24 being routed through the dip tankassembly 56 according an example embodiment. The dip tank assembly 56 iscapable of uniformly coating the liner 24 with the 1-partmoisture-curing urethane grout, for example an unactivated liquidpolyurethane. The dip tank assembly 56 is also able to apply the 1-partmoisture-curing urethane grout to liners 24 varying from 2 inches to 20feet in diameter, for example 6 inches to 12 inches in diameter. The diptank assembly 56 is robust in construction, easy to maintain andservice, and is portable in nature. As shown in FIG. 5, the dip tankassembly 56 includes a coating tank 58 which guides the liner 24 throughthe liquid polyurethane using a series of vertical and horizontalrollers 60. Guide rollers G are used to guide the liner 24 from a supplyinto the coating tank 58, and guide rollers G are again used to guidethe coated liner 24 from the coating tank 58 to a manhole where theliner 24 will be used to repair the damaged pipe 22. The coating tank 58is typically formed of aluminum and includes a removable top 62 and adrain 64. However, the design and the material used to form the coatingtank 58 can vary. The rollers 60 are typically formed of ultra-highdensity polyurethane. However, the dip tank assembly 56 could include adifferent array of rollers 60, and/or the rollers 60 could be formed ofdifferent materials. The dip tank assembly 56 also includes a mixingtank 66 acting as a reservoir to supply additional liquid polyurethaneto the coating tank 58 on demand to maintain the liquid level in thecoating tank 58. The mixing tank 66 can also be formed of aluminum, oranother material. Example specifications of the coating tank 58 and themixing tank 66 are provided in FIG. 6. These specifications are generalin nature and can be adjusted as required prior to fabrication of thedip tank assembly 56.

The TPU liner 24, with its exterior surface 26 soaked in the urethanegrout, is directed down into an opening of the host pipe 22. The TPUliner 24 is there attached to a spraying fixture 46 via thepuller/sealer fixture 48, as shown in FIGS. 3 and 4. The puller/sealerfixture 48 is a solid piece of material which serves as a mountingfixture which configures the liner 24 for optimal passage through thehost pipe 22, with minimal interference with the inner diameter surfaceof the host pipe 22. In the example embodiment, the puller/sealerfixture 48 has a U-shaped cross-section with no sharp edges. Thepuller/sealer fixture 48 maintains the liner 24 in an appropriateposition, without any sharp edges along the liner 24. In the exampleembodiment, the puller/sealer fixture 48 has an outer perimeter of23.560 inches, which is equal to the length of the 7.5 inch innerdiameter of the liner 24. Jigs or clamps 50 can be used to secure theliner 24 to the puller/sealer fixture 48. The puller/sealer fixture 48also prevents debris, moisture, and/or the grout material 30 fromentering the interior of the liner 24. For example, the clamps 50 cansecure the liner 24 tightly against the puller/sealer fixture 48 toprevent the debris, moisture, and/or the grout material 30 from enteringthe interior of the liner 24. During installation, the puller/sealerfixture 48 is attached to the rolling dolly 42 and pulled by the cable40 through the host pipe 22.

A set of the mixing/spraying heads 44 is also attached to the dolly 42and are pulled through the host pipe 22 during installation. Themixing/spraying heads 44 receive two urethane grout feed lines 52, 54routed from the pulling side, such as along the cable, that will mix the2-part grout before spraying the mixture onto the inner diameter surfaceof the host pipe 22. One feed line 52 includes the urethane and a secondfeed line 54 includes a curing agent. The rate of flow into themixing/spraying heads 44 will be controlled automatically as a functionof the velocity of the dolly 42 and the entire assembly through the hostpipe 22 so as to assure a consistent coating of the host pipe 22throughout. Thus, the area between the liner 24 and the host pipe 22 isfilled with both the 1-part and 2-part urethane grout. Once the fulllength of the TPU liner 24 has been pulled through the host pipe 22, theends of the liner 24 are capped, and the liner 24 is inflated to aspecific pressure. The grout material 30 is exposed to moisture, ultraviolet radiation, heat, and/or ultrasonics and thus cures and expands toadhere to the liner 24 and the inner diameter surface of the damagedpipe 22. The grout material 30 is typically in the form of a foam andbonds to the extruded liner 24, forming an adhesive and preferablycohesive bond, such that the plurality of flared tips 34 are notrequired for the liner 24 and grout material to maintain contact. Afteran appropriate curing period, pressure is released from the interior ofthe liner 24. Ends of the liner 24, as well as access points forlaterals (service lines), can then be trimmed.

Obviously, many modifications and variations of the present inventionare possible in light of the above teachings and may be practicedotherwise than as specifically described while within the scope of thefollowing claims.

The invention claimed is:
 1. An assembly for restoring a damaged pipe,comprising: a liner formed of a thermoplastic polyurethane, said linerincluding an exterior surface, said exterior surface presenting aplurality of flared tips and grooves, each groove being located betweenadjacent flared tips, a grout material disposed on said flared tips andin said grooves presented by said exterior surface of said liner, saidgrout material being expandable in a dimension upon exposure tomoisture, ultra violet radiation, heat, and/or ultrasonics; a cableattached to said liner and configured to pull said liner through thedamaged pipe; a puller-sealer fixture having a U-shaped cross-sectionconfigured to hold said liner while the puller-sealer fixture and theliner are pulled together through the damaged pipe; and a rolling dollyattached to the puller-sealer fixture for attaching the cable to thepuller-seal fixture and the liner.
 2. The assembly of claim 1, whereinsaid flared tips are located around an outer circumference of saidliner, each of said flared tips of said liner includes a stem extendingperpendicular to a base of said liner, each of said flared tips includesan enlarged top flaring outwardly relative to said stem, and saidenlarged top has a width greater than a width of said stem.
 3. Theassembly of claim 1, wherein said thermoplastic polyurethane of saidliner is clear.
 4. The assembly of claim 1, wherein said grout materialhas a volume which is 1% to 1000% greater after expansion by themoisture, ultra violet radiation, heat, and/or ultrasonics.
 5. Theassembly of claim 1, wherein said grout material includes polyurethaneand fibers.
 6. The assembly of claim 1, wherein said thermoplasticpolyurethane of said liner is clear, said liner includes a plurality offibers, said liner includes an interior surface opposite said exteriorsurface, said flared tips are located along said entire exterior surfaceof said liner and continuously around said outer circumference of saidliner, each of said flared tips of said liner includes a stem extendingperpendicular to a base of said liner and an enlarged top flaringoutwardly relative to said stem, said enlarged top has a width greaterthan a width of said stem, said grout material has a volume which is 1%to 1000% greater after expansion by moisture, ultra violet radiation,heat, and/or ultrasonics, and said grout material includes polyurethaneand fibers.
 7. The assembly of claim 1, wherein the liner is secured tothe puller-sealer fixture by clamps which prevent debris, moisture,and/or the grout material from entering an interior of the liner.
 8. Theassembly of claim 1, further comprising a spraying head attached to therolling dolly ahead of the liner and configured to spray a 2-parturethane grout onto an inner surface of the damaged pipe.